User guide

Chapter 6: Network Menu and Forms 45
UDP protocol fields
If UDP is selected as a protocol when specifying a rule, the additional fields shown in the following
figure appear at the bottom of the form.
Figure 6.14: Firewall Configuration Add Rule and Edit Rule UDP Protocol Fields
ICMP protocol fields
If ICMP is selected as a protocol, the ICMP Type pull-down menu is displayed in the ICMP
Options Section at the bottom of the Firewall Configuration form. Select the ICMP type needed
from the list.
Input interface, output interface and fragments
If an interface (such as eth0 or eth1) is entered in the Input Interface field, incoming packets are
filtered for the specified interface. If an interface is entered in the Output Interface field, outgoing
packets are filtered for the specified interface. The input and output interface fields are shown in the
following figure along with the options on the Fragments pull-down menu.
Table 6.3: Expert - TCP Options Fields
Field/Menu Option Definition
Source Port
- OR -
Destination Port
-AND-
to
A port number for filtering in the Source Port or Destination Port field. A range of
IP address can be specified by adding a second port number in the to field. TCP
packets are filtered for for the range of specified IP addresses.
TCP Flags The TCP flags cause packets to be filtered for the specified flag and the selected
condition. The flags are: SYN (synchronize), ACK (acknowledge), FIN (finish),
RST (reset), URG (urgent) or PSH (push) and the conditions are either Any, Set
or Unset.
Inverted By checking this box, the TCP options are Inverted. Inverting an item negates the
selected rules. Rules will apply to everything except the selected options.